Quick Bridge

[deepNdirt]

Last spring during some heavy rain the creek rises and the water got swift enough to wash away my old bridge, It was made from LVL beams and was 10 ft in length across the lower banks, I'd never would dreamed the rising water could had moved it,
Even now with the water way down I've not been able to find any sign of the old bridge structure,....
.
Now here's what I have in mind while at the salvage yard the other day I came across a 16 ft trailer frame, it was mission one of the two axles and in pretty rough condition, which would justify it being in the "junk Yard"
The owner of this place is asking $400 for the trailer frame, I figure this would be much cheaper than the cost of building materials to build one,

Can anyone see as to why I shouldn't use this frame to build a new bridge? sure would save some time and money appose to having to start from scratch, I would of course next time locate the bridge on higher banks so the water couldn't get to it,
My only use for the bridge is as before was to get my tractor and cutter across to keep the other side of my property mowed down, They're also been a very large Oak tree to fall across and I haven't a way to get over with my tractor to cut and move it,

I would say the most weight load would be of my tractor and possibly some tree chunks total weigh around 3300 lbs, would a 16ft trailer span across hold up this kind of weight? I realize that when hauling on a trailer most of the weight should be over the 2 axles and then the weight is transfered to the ground, But what about a open span? realistically the trailers two ends would be resting on about 1.5 ft of ground, Probably even more once I dig down, so the actual span would be more of 12-13 ft. and having it roughly 7-8ft high
What-y'all-think? can it be safe? or is bad idea?

 

[KennyG]

Should be workable. To be sure on capacity, I would suggest measuring the frame rails (dimensions and wall thickness) and check the safe load. It's a fairly simple calculation that anyone with an engineering handbook can do.

HOWEVER - I don't think $400 is a bargain. My guess is that you can laminate up treated 2x10's or 2x12's and get enough capacity a good bit cheaper. There are a lot of variables but with your 13 foot span, a single 2x12 would probably support around a ton of distributed load. Assuming your bridge would have about 6 of the 2x12s, even with the more localized loads of a vehicle, you would have at least 3 to 4 tons of very safe capacity. You can buy a lot of 16 foot long treated 2x12s for $400.

If you take a pair of treated 2x timbers and laminate a few strips of plywood or OSB between them, you get a tremendously strong beam.

 

[Western]

I think the "bargain" would be in longevity with steel over wood, but your still looking at decking cost. If the trailer has rails that adds a little strength and it wouldn't be to hard to add a bottom steel gusset brace or similar to beef it up.

Also you may want to set a steel post stub, (just at ground level) then weld a chain from it to the bridge, next time it floods you will be able to find it

 

[MotorSeven]

I agree, $400 sounds high. I have a 20' truck bed as a bridge...works great and can handle my 40 horse tractor. But, don't think the water can't wash it down stream. A mere 6" of fast moving water can push a small car sideways......water has a tremendous force. If you build some concrete buttresses at each bank well above the flood line you will be much better off. The higher the better because debris washed downstream and pushed against a bridge by the water is just as powerful as the water itself.

My bridge crosses a small creek but is parallel to a large creek. When the large creek floods, water flows across the bridge just like you drive across it. I thought this would not move it.....wrong, my 4 thousand pound bridge gets pushed back almost a foot every time we have a big flood. It's an easy fix with the tractor, but if that water was going perpendicular, the bridge would be down stream quite a ways.

 

[deepNdirt]

yeah I agree it might be a bit pricey if one were to be restoring it into a usable trailer, But for using the structure as a bridge I thought would be a big savings, I've estimated the cost going back with LVL beams and 2 x 6 decking, the cost was over $1200 , this trailer has wooded decking on it although would most likely have to replace half of them, to be honest this last bridge was the 2nd one I had to wash away, The first one was built from 3 sets of double pt 2 x 8's space @ 2 ft OC total 6 ft wide and had it decked with pt 2 x 6's .........................
I had one other idea of getting across the creek, but not sure if I am allowed to do it? to get a large cement culvert pipe, say about 5 ft. and roll it off over into the narrow part of the creek and fill in around it with gravel and cement, .... or perhaps lay a couple of smaller steel pipes side by side,
What ever it is I do I want it to be the last time and to last for more than 5-6 years,

 

[slowzuki]

Takes a much bigger culvert than you would think to put a stream through. The trailer is priced quite high and likely not strong enough to span 16 ft. As a trailer, the biggest span is from the hitch to the first axle, and there usually is not much weight up there without it being balanced behind the rear axle.

Here I've seen some mobile home frames used by cutting in half and stacking them. The local golf course has one full length that they left the axles on so they can put it back in place easier after it washes, but it bows pretty bad with just an electric golf cart on it, should be cut down.

 

[LD1]

I agree with others that it sounds high, but that depends on the trailer. You never were really clear on that.

If it is an old used equipment trailer with like 6" channel iron frame, then yea, its probabally not a bad deal and probabally strong enough.

But if it is a lower end car hauler (4" frame) or a landscape style (angle iron and side rails), then $400 is WAY too much and likely NOT strong enough.

$400 will go a long ways torward a real bridge or even a large culvert.

A 30' length of NEW I-beam to span your ~15' in two places and heavy enough to do the job shouldnt cost you more than ~$300-$400. Then all you have to do is deck it, which you said that you would have to do to about half the trailer anyway.

Without knowing exactally what kind of trailer you are talking about, it is hard to comment further. For all we know you are talking about 20' tag trailer made to haul a dozer:confused2:

 

[deepNdirt]

Thanks for all inputs, I am taking all into consideration,
Actually it looks to be made of 4" channel iron looks simi-heavy duty or at the least medium duty, it is very similar to the 16' X 6.6 trailer I have except mine is made from the angle iron as mentioned, I do believe it is an old landscape trailer because of its 2 x 2 iron side rails inverted all around it, something you wouldn't see on a heavier duty flatbed equipment trailers,
Question: could I not use the rail to diagonally X-brace into the bottom, for extra strength, I might try offering him 300 for it, with some luck maybe he'll meet me in the middle with 350 surely I would have much over 600-650 invested when through
Thanks

 

[Midwest Chuck]

For cost comparison: I put in a quick bridge this summer using a 20' truck flat bed from a truck salvage yard. Cost of the bed was $500 + tax, a wrecker to haul it 35 miles was $175, and a crane to set it in place was $260. So it came in at a tad under a grand.

I'm looking forward to seeing how it handles the winter flooding. I used 3" angle iron to anchor the corners, and the profile of the bridge is pretty narrow. On the other hand, quite a bit of water and some big debris comes through. The guy at the salvage yard had some military experience with quick bridges and said it would work. If it doesn't, I'll drag it back in place and shore it up better.

 

[LD1]

For a 4" channel iron trailer bridge @ $600-$650, I think I'd pass on the deal.

IMO, for the money, a better bridge can be built. Stronger, better looking, and longer lasting. But that is just my :2cents: